9.2 The Liver

Question 1

Where is the liver located?

Answer 1

Upper right portion of abdominal cavity
Beneath diaphragm
On top of stomach, right kidney and intestine

Question 2

Functions of the liver?

Answer 2

1) metabolism - anabolism (synthesis of plasma proteins like albumin), catabolism (cytochrome p450)
2) storage of nutrients (vit A, b12, D, K, carbs/fat - glycogen, triglyceride and lipoprotein)
3) exocrine - bile production - gall bladder - duodenum
4) endocrine - angiotensin and thrombopoietin, breaks down insulin, glucagon, oestrogen, progesterone
5) complete krebbs urea cycle - converts ammonia to urea which is secreted in the urine

Question 3

How many lobes does the liver have?

Answer 3

2 - divided by the falciform ligament

Question 4

Why is the liver brown?

Answer 4

Lots of mitochondria!

Question 5

What is the portal triad?

Answer 5

It consists of

1) portal vein - nutrient rich blood
2) hepatic artery - oxygen rich blood
3) hepatic duct - synthesises and secretes bile

And it supplies blood to the liver

Question 6

What is a portal system and where can they be found in the body?

Answer 6

Two capillary beds can be found in series

Hepatic portal system and hypothalamus-hypophyseal portal system

Question 7

What is a hepatocyte?

Answer 7

Liver cells - regeneration great!

Question 8

What is the function of the portal vein?

Answer 8

Supplies the liver with nutrient rich blood.

It carries : water, water soluble vitamins, electrolytes, carbohydrates, pancreatic hormones, toxins: bacteria, viruses, protozoa, nematodes, cestodes, ammonia (broken down into urea then secreted into urine)

Does not carry:

• lipids (taken up into cell, processed into chylomicrons)
• fat soluble vitamins (A, D, E, K)

Question 9

What is a chylomicron?

Answer 9

Transport lipids absorbed from intestine to adipose, cardiac and skeletal muscle tissue where components hydrolysed allowing release of the fatty acids to be absorbed by tissues.

They’re taken up by lymphatics called lacteals which contain chyle (mixture of lymph and chylomicrons).

Question 10

What is the function of the hepatic artery?

Answer 10

Supplies oxygen to the liver

Question 11

What is the function of the hepatic vein?

Answer 11

Carries blood away from the liver which is both nutrient and oxygen poor - to the IVC

Question 12

What are kupffer cells and their function?

Answer 12

1. Monocyte derived specialist macrophages
2. Form part of lining of sinusoid
3. For gut-derived bacteria, microbial debris and bacterial endotoxins

Question 13

What are stellate cells and their function?

Answer 13

1. They contain many cytoplasmic vacuoles containing vit A.

2. For nutrition

Question 14

How does liver cirrhosis occur?

Answer 14

1. Stellate cells lose ability to store vit A and differentiate into myofibroblasts
2. These secrete collagen in perisinusoidal space causing liver fibrosis
3. Central vein becomes blocked causing portal hypertension

Question 15

What is a liver Acinus?

Answer 15

A functional unit of the liver i.e.
Diamond shaped from central vein of one liver lobule to adjacent central vein of another lobule.
Includes the following: Hepatocytes, Central vein, portal vein, hepatic artery and hepatic duct (kupffer and Stellate cells)

Question 16

What is bile?

Answer 16

A greenish brown alkaline fluid secreted by the liver, stored in the gall bladder, discharged into the duodenum to digest fats/lipids.

It’s made of Cholesterol, bile salts, bilirubin

Question 17

What is a sinusoid?

Answer 17

Blood vessel serving as a location to mix oxygen and nutrient rich blood to serve to hepatocytes in liver. Waste and deoxygenated blood leaves via central vein.

Question 18

What is the name of the vessel that carries bile from the hepatocytes to the hepatic duct?

Answer 18

Bile canaliculus